/*
 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 *
 *
 *
 *
 *
 *
 */

package java.util.zip;

import java.nio.file.attribute.FileTime;
import java.util.Date;
import java.util.concurrent.TimeUnit;

class ZipUtils {

  // used to adjust values between Windows and java epoch
  private static final long WINDOWS_EPOCH_IN_MICROSECONDS = -11644473600000000L;

  /**
   * Converts Windows time (in microseconds, UTC/GMT) time to FileTime.
   */
  public static final FileTime winTimeToFileTime(long wtime) {
    return FileTime.from(wtime / 10 + WINDOWS_EPOCH_IN_MICROSECONDS,
        TimeUnit.MICROSECONDS);
  }

  /**
   * Converts FileTime to Windows time.
   */
  public static final long fileTimeToWinTime(FileTime ftime) {
    return (ftime.to(TimeUnit.MICROSECONDS) - WINDOWS_EPOCH_IN_MICROSECONDS) * 10;
  }

  /**
   * Converts "standard Unix time"(in seconds, UTC/GMT) to FileTime
   */
  public static final FileTime unixTimeToFileTime(long utime) {
    return FileTime.from(utime, TimeUnit.SECONDS);
  }

  /**
   * Converts FileTime to "standard Unix time".
   */
  public static final long fileTimeToUnixTime(FileTime ftime) {
    return ftime.to(TimeUnit.SECONDS);
  }

  /**
   * Converts DOS time to Java time (number of milliseconds since epoch).
   */
  private static long dosToJavaTime(long dtime) {
    @SuppressWarnings("deprecation") // Use of date constructor.
        Date d = new Date((int) (((dtime >> 25) & 0x7f) + 80),
        (int) (((dtime >> 21) & 0x0f) - 1),
        (int) ((dtime >> 16) & 0x1f),
        (int) ((dtime >> 11) & 0x1f),
        (int) ((dtime >> 5) & 0x3f),
        (int) ((dtime << 1) & 0x3e));
    return d.getTime();
  }

  /**
   * Converts extended DOS time to Java time, where up to 1999 milliseconds
   * might be encoded into the upper half of the returned long.
   *
   * @param xdostime the extended DOS time value
   * @return milliseconds since epoch
   */
  public static long extendedDosToJavaTime(long xdostime) {
    long time = dosToJavaTime(xdostime);
    return time + (xdostime >> 32);
  }

  /**
   * Converts Java time to DOS time.
   */
  @SuppressWarnings("deprecation") // Use of date methods
  private static long javaToDosTime(long time) {
    Date d = new Date(time);
    int year = d.getYear() + 1900;
    if (year < 1980) {
      return ZipEntry.DOSTIME_BEFORE_1980;
    }
    return (year - 1980) << 25 | (d.getMonth() + 1) << 21 |
        d.getDate() << 16 | d.getHours() << 11 | d.getMinutes() << 5 |
        d.getSeconds() >> 1;
  }

  /**
   * Converts Java time to DOS time, encoding any milliseconds lost
   * in the conversion into the upper half of the returned long.
   *
   * @param time milliseconds since epoch
   * @return DOS time with 2s remainder encoded into upper half
   */
  public static long javaToExtendedDosTime(long time) {
    if (time < 0) {
      return ZipEntry.DOSTIME_BEFORE_1980;
    }
    long dostime = javaToDosTime(time);
    return (dostime != ZipEntry.DOSTIME_BEFORE_1980)
        ? dostime + ((time % 2000) << 32)
        : ZipEntry.DOSTIME_BEFORE_1980;
  }

  /**
   * Fetches unsigned 16-bit value from byte array at specified offset.
   * The bytes are assumed to be in Intel (little-endian) byte order.
   */
  public static final int get16(byte b[], int off) {
    return Byte.toUnsignedInt(b[off]) | (Byte.toUnsignedInt(b[off + 1]) << 8);
  }

  /**
   * Fetches unsigned 32-bit value from byte array at specified offset.
   * The bytes are assumed to be in Intel (little-endian) byte order.
   */
  public static final long get32(byte b[], int off) {
    return (get16(b, off) | ((long) get16(b, off + 2) << 16)) & 0xffffffffL;
  }

  /**
   * Fetches signed 64-bit value from byte array at specified offset.
   * The bytes are assumed to be in Intel (little-endian) byte order.
   */
  public static final long get64(byte b[], int off) {
    return get32(b, off) | (get32(b, off + 4) << 32);
  }
}
